Liquid-operated electric switch



W. H. SWHTH.

LIQUID OPERATED ELECTRIC SWITCH.

APPLICATION FILED. DEC. 12, 1916.

1,840,086, Patented May 11, 1920.

Snow 61,

UNITED STATES PATENT OFFICE.

WILLIAM HOGG SMITH, OF FALKIRK, ENGLAND, ASSIGNOR TO THE FILBAR ELECTRICHEATER, LIMITED, OF LONDON, ENGLAND.

LIQUID-OPERATED ELECTRIC SWITCH.

Specification of Letters Patent.

Patented May 11, 1920.

Application filed December 12, 1916a Serial No, 136,556.

To all whom it may concern:

Be it known that 1, WILLIAM Hose SMITH, of #57 Orchard street, Falkirk,Stirlingshire, England, merchant, have invented certain new and usefulImprovements in Liquid- Operated Electric Switches, and do herebydeclare the nature of this invention and in what manner the same is tobe performed to be particularly described and ascertained in and by thefollowing statement.

This invention relates to a liquid operated switch particularly suitablefor controlling the supply of liquid to and the suppply of electriccurrent to electrical apparatus for heating liquid.

The present invention consists in a switch comprising a flexiblediaphragm influenced by liquid pressure and cooperating with contactsarranged to close when a predetermined pressure of liquid is reached andmaintained and to break when the pressure exceeds maximum or is reducedbelow minimum.

The invention is illustrated diagrammatically in the accompanyingdrawing in which the figure is a longitudinal section of a fluid conduitequipped in accordance with the invention.

As shown, the switch comprises a diaphragm 1 the side 2 of which issubject to liquid pressure controlled by a tap (not shown). Resting onthe side remote from the liquid pressure side is a rod at of insulatingmaterial such as vulcanite, such rod 4: penetrating a plate 8 ofinsulating material and engaging a spring loaded rocker 5.

The rocker 5 is fitted with a contact 6 engageable with a spring arm 7,which, in

turn, contacts normally with a contact 8. The arrangement is such thatwhen the diaphragm is bulged by liquid at the normal pressure, therocker 5 is moved by the rod 4 until the contact 6 contacts with the arm7 and the circuit through the elements 5, '6, 7, S is closed.

lVhen the pressure is below normal, no contact is made between thecontact 6 and the arm 7 and, when the maximum working pressure isexceeded, the arm is constrained to occupy a position such that the endremote from the contact 6 is out of contact with the contact 8 wherebythe circuit is broken.

The contact 8 and the rocker 5 represent remote ends oi an electricalcircuit including a solenoid (not shown) which operates the main switchof the electrical apparatus for heating the liquid which influences thediaphragm 1.

I claim In a device of the type described, the combination of a conduithaving a lateral dia phragm chamber, a diaphragm secured in the chamberand flexible by the water pressure in the conduit,.a superposed plateextending across the diaphragm and formed with an aperture, a rodseating on the diaphragm and extending through the aperture of the plateto be guided thereby, a switch arm movable by the rod, a fixed contact,and a second switch arm normally engaging the contact and adapted to beengaged by the first switch arm and to be disengaged thereby from thecontact.

The foregoing specification signed at Glasgow, this eighth day ofJanuary, 1917.

WILLIAM HOGG SMITH.

